Self-assembled monolayers formed by adsorption of 4-methyl-4‘-mercaptobiphenyl, CH3-(C6H4)2−SH (BPT), on Au(111) have been studied using scanning tunneling microscopy. The results show that with increasing coverage (resulting from longer immersion times) BPT forms a series of different structural phases with different molecular arrangements, closely resembling the behavior reported previously for n-alkanethiolate adlayers. For short immersion times, striped structures are observed (α and β), where the molecules are orientated with their axes parallel to the surface. Longer immersion times yield additional phases, namely, an ordered χ-phase, where the molecules are proposed to be oriented with their molecular axis tilted away from the surface, a disordered δ phase, and, finally, a densely packed (2√3 × √3) ε phase where the molecular axes are orientated almost upright. Unexpectedly, for BPT after adsorption small islands are seen on the Au substrate instead of the etch pits commonly observed after formation of organothiolate adlayers.

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Exposure of the mixed-terminated surface to atomic hydrogen at room temperature is found to lead to drastic changes of the electrical properties. The insulator surface is found to become metallic. By employing several experimental techniques (electron energy loss spectroscopy, He-atom scattering, and scanning tunneling microscopy) together with ab initio electronic structure calculations we demonstrate that a low-temperature (1 x 1) phase with two H atoms in the unit cell transforms upon heating to another (1 x 1) phase with only one H atom per unit cell. The odd number of electrons added to the surface per unit cell gives rise to partially filled surface states and thus a metallization of the surface.

It has been pointed out to the authors that there is at ypographical error in the theoretical part of the experimental section of the original Communication. Specifically, the metal supercell used in the theoretical calculations was 5 ” 5i nstead of the published 4 ” 4. The resulting simulation cell was thus a4” 4(bi-)layer of ZnO on 2 layers of 5 ” 5C u(111). As also later pointed out by Bieniek et al. [1] this yields alattice mismatch between the two materials of only ca. 1% in order to strain the resulting ZnO overlayer structure as little as possible. The structures given in the abstract picture, Figure 3and the coordinates in the Supporting Information show the correct 4 ” 4ZnO @5” 5Custructure.

The oxidation of CO over Ru/MgO and Ru/SiO2 catalysts was used as a simple model reaction to derive turnover frequencies at atmospheric pressure, which were observed to agree with kinetic data obtained under high-vacuum conditions with supported ruthenium catalysts and the RuO2(110) single-crystal surface. Thus, it was possible to bridge both the pressure and the materials gap. However, a partial deactivation was observed initially, which was identified as an activated process, both under net reducing and net oxidizing conditions. Temperature-programmed reduction (TPR) experiments were performed subsequently in the same reactor, to monitor the degree of oxidation, as a function of the reaction temperature and the CO/O2 reactant feed ratio. Using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements, the structural changes of the ruthenium catalysts during the oxidation of CO were confirmed, under relevant reaction conditions. Under net reducing conditions, only domains of RuO2 seem to exist on the metallic ruthenium particles, whereas, under net oxidizing conditions, the ruthenium particles were fully oxidized to bulk RuO2 particles, which may expose less-active facets, such as the RuO2(100)−c(2 × 2) surface.